The main functions of a ROM include storing programs and software instructions in electronic devices as well as performing major input and output tasks. Short for read-only memory, ROM is a type of memory storage system that can only be read and not modified. ROM is also referred to as a nonvolatile memory storage.
Read-only memory is essential in a personal computer, or PC, as it contains the data instructions needed to start and boot it up. ROM also holds the software instructions needed by the PC to perform basic data management tasks, to access and send instructions to internal computer devices, such as hard disk drives, optical drives and graphic cards, and for some of the basic functions of a computer application.
Apart from the PC, read-only memory is also used in other electronic devices, such as calculators, printers, home appliances and MP3 players. By 2008, most electronic devices use flash type memory instead of ROM, to enable the device to be updated with the latest firmware versions.
There are several types of ROM modules, with the most common one being the masked-type ROM, where the data is encrypted during fabrication. Other types include the programmable read-only memory where the data can be written or programmed once after fabrication, and erasable programmable read-only memory where the data can be erased and rewritten into the module using a highly complex process.